This invention relates to television transmission and reception and, more particularly, to a method and system for transmission and reception of high definition television information.
As high definition television (HDTV) becomes more prevalent, improved systems are needed for transmission and reception of the additional information required for presenting HDTV images. A number of HDTV schemes have been proposed. In my U.S. Pat. Nos. 4,517,597, 4,628,344, and 4,652,909, and my U.S. patent application Ser. No. 005,296, as well as in my publication "HDTV Compatible Transmission System", National Association of Broadcasters, April, 1986, there is disclosed an HDTV system that utilizes a "two signal" approach which permits compatible transmission of HDTV. For operation in NTSC, one signal would carry the standard 525 line NTSC transmission, and a second signal would carry detail signals that can be received by receivers having HDTV capability and suitably combined with the standard signals to obtain HDTV signals for display. As described in my referenced patents, application, and publication, the detail signal can be sent at a reduced frame refresh rate, thereby saving substantial bandwidth. Nonetheless, at least a portion of an additional TV transmission channel is needed for transmission of the detail signal. In other proposed systems, the enhancement signal may take forms other than the type of detail signal described in my above referenced patents and application but, again, at least a portion of an additional television transmission channel will be needed for transmission of the enhancement signal.
If an expanded channel or an adjacent channel is available for transmission, the enhancement signal can be sent thereon. However, for various reasons, such as channel availability, it may sometimes be desirable to send the enhancement signal over a channel that is not adjacent to the channel being used to send the standard or main portion of the HDTV signal.
Representative prior art patents, which deal with topics including transmission of HDTV signals, the transmission of coded information with television information, transmission of auxiliary information with television signals, and addressing of television receivers, are set forth in U.S. Pat. Nos. 3,493,674, 4,292,650, 4,535,352, 4,323,922, 4,567,508, 4,567,531 and 4,581,640.
It is among the objects of the present invention to provide improvements in systems and methods for transmission of HDTV signals, particularly where enhancement signals are transmitted over a channel that is not adjacent to the channel carrying the standard or main portion of the HDTV signal.